Method of firing furnaces.



G. L. PRBNTISS.

METHOD OF FIBING FURNACES. APPLIOATION FILED SEPT. 14. 1907.

Patented Aug. 17, 1909.

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ATTO/?NEYS W/TNESSES G. L. PRENTISS.

METHOD OF FIRING FURNACES.

APPLIOATION rILED SEPT. 14, 1907.

93 1,645, w Patented Aug. 17, 1909.

2 SHEETS-SHEBT 2.

W/TNESSES W [MENTOR UNITED STATES %PATENT OFFTCE GEORGE L. PRENTISS, OF MONTGLAIR, NEW JERSEY.

METHOD OF FIBING FURNACES.

To all whom tt may concem:

Be it known that I, GEORGE L. Pennrrss, a citizen of the United States of America, residing at Montclair, New Jersey, have in vented certain new and useful lmprove ments in Methods of Firing Furnaces, of which the following is a specification.

My invention relates to an improved method for ring blank and other furnaces, with special reference to brick kilns,whereby certain desirable conditions of combustion may be obtained in the furnace, or in the blank or heating chamber of the furnace.

More particularly, the invention relates to the maintenance of these conditions of employing as the source of heat a gas producer conducted and operated in a peculiar and novel nanner.

in the burning of brick and other refractory material for instance there appear to be certain laws relating to combustion to be observed if the best product is to be obtained. A departure from these laws involves an inferior product. Itis desirable, for instance, that the gases burning in a brick kiln be under pressure and the same is true of every heating furnace; otherwise, they take the shot-test path to the stack, and the brick or other material is not unifornly atiected by theni. Suitable pressure, howcve will cause the burning 'ases to engage the brick or other material over all exposed sui-faces alike and in the most effective manner. Again, certain kinds of brick for instance, seem to be peculiarly sensible to changes of temperature and to need a carefully adjusted and uniforinly progressive temperature, and to be susceptible to in'jury by an excess of improperly burned or heated oxygen. lt seems desirable that a certain carefully graduated progression of temperature be had in a brick kiln, and that the ten'perature conditions be uniforin, and that there be no contact with the brick of unburned oxygen. These considerations apply with equal force to the burning or heating of other material than brick.

Attempts to maintain in a kiln or heating chaniber, a proper pressure, a uniformity of temperature, determined rise or progression of temperature, and the other desirable conditions of combustion have not been lacking. Attempts have also been made to obtain these conditions by the einployment of gas producers and stean blasts in various manners. For one reason or other, however, the

Specificaton of Letters Patent.

Application filed September 14, 1907.

Patented Aug. 17, 1909.

Serial No. 392,898.

desired conditions have not been satisfactorily obtained. Particular diticulty seems to have been experienced in the use of gas producers and steain blasts. Bricks heretofore produced by processes in which these have been employed have been checked, cracked or discolored or the cost of operation has been found too high. Other material has been variously and injuriously affected when treated by these processes.

here a grate fire of the usual kind, or any other thin fire, has been heretofore einployed, particularly when in connection with a steam blast, the material being treated has often been injured. The most probable reason for this seems to be that it is difficult with fires of such a nature to prevent the burning or blowing of holes through the fuel and the consequent adnission into the heating chamber through such holes of unburned oxygen or free air and steam, in eXcess.

The adnission of cold air to the heating chamber is especially likely to Occur in furnaces as heretofore constructed when the door is opened to supply fresh fuel, or when the ash-pit door is opened to remove ash. The admission of cold air at such times, besides cooling the heating chainber and causing undesirable fiuctuations of temperature therein, results in a waste of heat and lengthening of the time required for heating the material.

I have discovered that a certain combination of gaseous elements so treated that, after being emitted from the furnace and intimately mixed and brought to a state of uniforni temperature, and then fed to the kiln under pressure, will produce in the heating chamber or kiln a condition of combustion which has heretofore not been attained, which is eminently satisfactory for the burning of brick and other material. More particularly, I have found that, by constructing my furnace in connection with a steam blast in such a way that no eXcess of unbnrned oxygen, cold air, or steam can be admitted to the heating chamber, the proper conditions of uniformity of temperature, pressure and conbustion may be obtained.

In the embodiment of my invention hereinafter to be described in detail, there is employed a steani blowcr or blowers for supplying steam to the fire and for maintaining a pressure in the kiln or other heating chamber, suflicient to cause the burning gases to engage the material uniformly. Interposed between the main or primary blower of which there is at least one to each furnace and the heating chamber is the fire, which, in this instance, consists of a mass of burning coal tamped or packed to considerable depth in a comparatively narrow passage forming the fire chamber, and opening at one end into the heating chamber. At the other end of the passage is the ash-pit into which the blower ejects the steam and air under pressure. At a point of the fire chamber intermediate the ends of the fuel column, I provide an opening through which the fire may be fed and tamped or packed. This opening may be provided with an eX- terior sealing door which is closed except when fuel is being fed or tamped through the opening, and which when closed prevent-s any passage of air, gases or other fluids through the opening. The presence of such a door is not always a necessity as the fuel itself (in its unburned condition) frequently forms an effective barrier to the passage of air. The fuel column being fed or tamped from an intermediate point of the same, the portion of the fuel above the feed openings serves to seal the heating chamber against the admission of cold air at the time the furnace door or hopper is open for feeding or tamping. In the furnace shown I employ no grate. As the fuel burns, and the ash and clinkers must be removed at the pit, other fuel may be supplied through the pit as necessary into the part of the fuel column previously occupied by the ash removed. The opening to the ash-pit is also normally closed by a scaling door to prevent the passage of air, steam, or gases through the same when the blower is in operation. As the column of packed fuel drops or is burned away, new fuel is packed in through the intermediate and sometimes also the ash-pit openings rei'erred to in order that the length and homogeneity of the column may be maintained.

Owing to the depth and solidity of the fuel. column, no holes are burned or blown through it, and no opportunity is offered for unburned oxygen or excess steam to reach the kiln or other heating chamber from the pit. All air and steam nust pass from end to end through the column of closely packed. fuel and be thoroughly and uniformly heated and mixed with the other gaseous constituents before being delivered to the heating chamber. The steam, when thus heated and intimately mixed with the other gases, in addition to providing the pressure for the heating chamber, produces therein, by reason of the hydrogen forming one of its elements, a condition of long, burning flames which seem to be peculiarly beneficial to brick and many other materials capable of being thus treated. The closely packed column acts as a regulator to prevent any fiuctuation of temperature within the kiln or other chamber such as might otherwise occur through the burning of holes through the fuel, or upon the opening of the furnace and doors. The temperature in the heating chamber or kiln is maintained substantially uniform throughout its area and said temperature may be progressively raised. Properly managed, it can never drop so that the brick or other material will be injured by the condensation of steam thereon by the interruption to the duly progressive rise or the uniformly maintained temperature which may be needed in the particular case, or by the other incidents of an uncertain or fiuctuating temperature accompanied by free air and mproperly burning gases.

The progressve burning of a solid column of fuel., as has been described, will with all fuels bring about the progressive accretion or deposition of ash or clinker, or both combined at the base of said column. Sometimes this clinker becomes too hard or too glutinous and ropy 77 for satisfactory handling, and it is necessary to adopt means for its treatment of an extraordinary character. One of such means is the placin in the ashpit upon the floor or hearth of the furnace of fresh coal after the removal of suflicient clinker to clear the furnace and enable it to further consume fuel. The oflice of such coal placed in the ash-pit is to there burn as a result of its ignition by radiated heat, and by giving oli its own heat, melt or make plastic clinker above it, which may have hardened unduly. Another of such means is the supplying of subsidiary blowers, the location of which, with reference to the body of the fuel, is determined by the stage of combustion of the various parts of the fuel column. One or more of such subsidiary blowers may be so located as to drive air and stean (by an injector blower) or air alone (by the use of a fan or other prope'ller) directly upon the incandescent bed of coal in a line substantially parallel with the line at which ash forms in the furnace and directly above it. The result of this treatment is in many instanccs to prevent clinker, where under any other method of treatment clinker would form and to raise the furnace temperature where desirable. The reason for this is tl at the hydrogen and air take heat very rapidly from the fuel just forming into ash and do it at such a time and in such a manner that sucient heat does not there exist to cause the ash to run together into clinkers. `When the ash drops down and away from the bed of fire, it becomes progressively cooler and thus never has an opportunity to vitrify and is nltinately removed as ash.

Having set forth brietly the objects and nature of my invention, I will now describe Fig. 3 represents a still later and perhaps the normal condition of conbustion after the fire is fully under way. Eig. -it shows the aiplicant s method of representing in Figs. 1, 2 and the tresl ani i tuel, and ash and clinkers.

i w. Dallimi&

Referring to Figo. 1, 2 and 3 the furnace' conbustion chaniber is illustrated at l, terninating atits lower end in the ash pit 2 and at its upper end opening through the passa ge 3, into the blank or hee` ing chanber 4 of a brick hihi or other turnace. The burning gases froni the conbustion clnnnber are directed to any desircd part ot the heating chan'hcr by ineans ot the partition or wall the shape and position of which nay be 'a 'ied at will. This means ot' directing the gases to a desired partot the chalnber is of importance as heretotore stated. In brick kilns tor exanplm I have found it extremely desi 'able that the ;IHSGS enter the clnunber above the brick and circulate over and down through the same instead of entering below the brick. The wall 5 accordingly shown as carried well above the floor 5 ot the chanber, ou which brit-l is stacked.

The tur'ace is shown as having an opening' (3 through the front wall into the conbusticn' chan'iber 1 :it a point intermediate the ends ot the letter. ?he opening; t is provided with a norinully cloz-:ed tiuid scaling; door 7. The opening S into 'the ash pit is siinilarly provided with a tiuid sealin door i). The doors 'i' and S) when closed prevent, passa e to or froni the iturnace through the openii C and S of any air, gas stean or other hnd. bler-.er is located at the point 10 ot the fire-pit. Through this the air and stcain necessary to the coinbnstion is injected into the 't'urnace Ste-an' is supplied to the blower by a pipe 11 f i run a boiler, the pipo ll being; led through the Vaills of the heating chaniber before teruinatng et the blower in order that the steain niay be ettectively superheated before its injection into the turnace. The blower is also in connection with au air supply passage, and this passage also passes through the ti rnace betorc terminating at the blower. The superhenting of the air and steain is of considerable inpm'tance to the process ot this invention.

In carrying' out the process ot the invention the turnace is first filled, with wood, and a fire started. As the fire underway, coal 12 is supplied through the opening G to u level 13 in the cornbustion chmnber blower is again put in operation.

above such opening, the door 7 being opened tor this purpose. rs the coni burns ash and clinke' will collect in the fire pit as illustrated at in i l. After the coal 12 is burning well throughout its inass the door 7 is again opened and a freseh body of coal 15 t'ed in and tanped through the burning coal 12. ile-;ruse ot the level 13 at which the coai is nninteinwh no air can reach the heating chainber -l when the door 7 is opened 'tor teedi and tan'ping in the fresh coal 15 unless such air first pnsscs through the burning conl l. in passing through the burning; coal 12, any such air will be burned, and it cannot reach the brick or other material in the chznnber -t in cold or unburned conditions. Air 'tor conbustion ot torined in this turnace nnrv, ot course, be supplied in any suitable mann-er, annlogous to the procemploved in regcnerative or rccnperaiirc chanbcrs or turnaces, or directly to the blank chauher or solelv through the lire beh as tie circnnistanccs nnrv requirc. The bler-;er V now shut oti tin ash pit door opened, und the ash and clinker 12 removed t'roin the ash pit. The soliditv with which.

', 15 is oachcd together with the fact 'i e t me clinlzer tends to toi-in a solid bridge 'l aver the ash-pit (se-e Fg. prevents the t 'l into the ash pit 'uel cohunn r ren the .i i and chnker 12 are removed troin the san'e. Fresh fuel 17 (see now 3) s then tcd into the ash pit as nay be needed through the opening S und pecked there'n nndcrthc tnel colunn lun-nur;` above.

: the cliuher l'u'idge or arch lt as shown is well developed et this st 'e ot the conihustim. l'hilc the door i) or the ash is open any air entering the same nust pass tl'rough the burning cohunn abovc and be lu h in;

thorm hlv heuted or burned before it reaches the chainber :h so t hatherc again the brick or oher material protected froni cold or *uburned uir. The d pth and solid- 'itv ot the cohrnn it' burning 'uel elininates, ot course, the nossibility ot ti e air entering at 8, blowing holcs through the *tnel and escaping through such holes 'in a relatively cold condition to the chtnnbcr t. Such holes could be blown through e thin fire such as the ordinary grate lire but never through such fire as is here einplovcd. Bitter the tuel 16 is supplied and the door 9 closed the As the fire continues to burn the opcr'tions hereto- 'tere described are rc eated when necessary. The *fresh 'fuel lt under the clinker bridge atthe ash pit burns nore 'apidlv than thc *Fresh 'tuel supplied through the door (S, and inust 't 'oni time to tine be reucwed, but before each renewal the ash and clinker nust be removed. As the 'fuel 12 above the clinker bridge 10 burns away, new tuel is tanped in through the door (3. It ciinker becomes so troublesone that the method just referred to is difficult, the placing of blower or blowers intermediate between the ends of the column of fuel and at about the point where ash norn'ally begins to form in the column is very beneficial.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is:

l. The method of firing furnaces consisting in pacl ing with fuel the passage which Supplies the burning gases to the heating ehamber. in iuaintaining the fuel so packed in active combustion by a draft through part of the same, withdrawing the ash from the ash pit end of the fuel column, feeding fresh fuel to an intermediate point of the column and tamping the same to maintain the column compact and homogeneous.

The method of thing furnaces consistiig in packing with fuel the passage which supplies the burning gases to the heating chamber, in maintaining 'the fuel so pacled in active combustion by a blast of air and steam through part of the same, withdrawing the ash from the ash pit end of the fuel column, feeding fresh fuel to an intermediate point of the column and tamping the same to maintain the column compact and homogencous.

3. The method of firing furnaces consisting in packing with fuel the passage which supplies the burning gases to the heating chanibei', in maintaiuing the fuel so packed iu active combustion by superheated steam and air through part of the same, withdrawing the ash from the ash pit end of the fuel column, feeding fresh fuel to an intermediate pointef the column and tamping the same to maintain the column compact and homogeueous.

r he method of firiug furuaces consisti ;g iu paehiug with fuel the passage which supplies the burning gases to the heating chamber, maintaining the fuel so packed in active combustion by a draft therethrough, withdrawing the ash from the ash-pit end of the fuel column, feeding fresh fuel to an intermediate point of the column and tamping the same to maintain the column compact and homogeneous.

5. The method of firing furnaces consisting in packing with fuel the passage which supplies the burning gases to the heating ehamber, maintaining the fuel so packed in active combustion by a blast of steam and air therethrough withdrawing the ash from the ash-pit end of the fuel column, feeding fresh fuel to an intermediate point of the column and tamping the same to maintain the column compact and homogeneous.

(i. The method of ring furnaces consisting in packing with fuel the passage which supplies the burning gases to the heating chamber, maintaining the fuel so packed in active combustion by a blast of superheated steam and air theretln'ough, withdrawing the ash from 'the ash-pit end of the fuel column, feeding fresh fuel to an intermedi- 'ate point of the column, tamping the same to maintain the column compact and homogeneous.

7. The method of firing furnaces, consisting in packing with fuel the passage which Supplies the burning gases to the heating chamber, nuintaining the fuel so packed in active conbustion by a draft therethrough, withdrawing the ash from the ash-pit end of the fuel column, substituting fuel at the ash-pit end of the column for the ash removed, feeding fresh fuel to an intermediate point of the column and tamping the same to maintain the column compact and homogeneous.

8. The method of firing furnaces c0nsisting in packing with fuel the passage which supplies the burning gases to the heating chamber, maintaining the fuel so packed in active combustion by a blast of steam and air theretin'ough, ii 'ithdrawing the ash from the ash-pit end of the fuel column, substituting fuel atthe ash-pit end of the column for the ash removed, feeding fresh fuel. to an 'intermediate point of the column and tamping the same to maintain the column compact and homogcneous E). The method of firiug furnaces, consistiug in paching with fuel the passage which supplies the burning gases to the heating chamher, n'aintainiug the fuel so pac-lied 'in active combustion by a blast of superheated steam and air therethrough, withdrawing the ash from the ash-pit end of the fuel column, substituting fuel at the ash-pit end of the column for the ash removed, feeding fresh fuel to an intermediate point of the column, tamping the same to maintain the column compact and homogeneous.

Signed by me at New York city this 13th day of September, 1007.

GEORGE L. PRENTISS.

lVitn esses Jaooe I. BERGEN, lnssm M. llanms. 

